Guidance means for a rotary engine or pump

ABSTRACT

The invention provides a rotary engine or pump of the type comprising a body with an internal epitrochoidal cross-section chamber and a triangular cross-section rotor rotatable in the body chamber so as to form a plurality of working chambers that vary in volume upon relative rotation of the rotor and the body. A new guidance means for guiding the rotor in the required motion relative to the body comprise a first planar guide surface of essentially triangular shape movable with the rotor and a second planar guide surface movable with the body, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being of oval shape generated by the said first surface in their required relative motion. A seal for use between each rotor apex and the chamber wall comprises two co-operating seal members urged radially outwards by operating fluid of the mechanism.

[4 1 May 20, 1975 GUIDANCE MEANS FOR A ROTARY ENGlNE OR PUMP HerbertLewis Gray, Milton, Ontario, Canada [75] Inventor:

[73] Assignee: Gray & Bensley Research Corporation, Milton, Ontario,Canada 22 Filed: Nov. 8, 1973 [21] Appl. No.: 414,000

Primary ExaminerJohn J. Vrablik Attorney, Agent, or Firm-Stanley J.Rogers [57] ABSTRACT The invention provides a rotary engine or pump ofthe type comprising a body with an internal epitrochoidal cross-sectionchamber and a triangular cross-section rotor rotatable in the bodychamber 50 as to form a plurality of working chambers that vary involume upon relative rotation of the rotor and the body. A new guidancemeans for guiding the rotor in the required motion relative to the bodycomprise a first planar guide surface of essentially triangular shapemovable with the rotor and a second planar guide surface movable withthe body, the guide surfaces being in relatively-sliding engagement withone another, the said second surface being of oval shape generated bythe said first surface in their required relative motion. A seal for usebetween each rotor apex and the chamber wall comprises two co-operatingseal members urged radially outwards by operating fluid of themechanism.

6 Claims, 16 Drawing Figures PATENTEU HAY20 197s 8 84, 6 O 0 sum 10F 4PATENTEU MAY 2 01975 SHEET 3 [)F 4 FIELD OF THE IN VENTION The presentinvention is concerned with improvements in rotary mechanisms of thetype operable as an engine or as a pump or compressor.

REVIEW OF THEPRIOR ART Of the very large number of rotary engines thathave been proposed hitherto only one has at this time achieved anysubstantial commercial success, namely that known as the Wankel rotaryengine, as described, for example, in US. Pat. Ser, No: 2,988,065,issued June 13, 1961 to N.S.U. Motorenwerke AC. and Wankel G.m.b.H., andalso in the book The Wankel Engine by Jan P. Norbye, published 1971 byChelton Book Co., Library of Congress Cataloque Card No: 73-161624.

The most usual form of Wankel engine consists of one or more three-lobedhypotrochoidal cross-section rotors mounted for orbital motion within atwo-lobed epitrochoidal cross-section chamber in the engine casing. Therotor rotates freely by means of an interposed bearing upon an eccentricportion of a main output shaft, this eccentric mounting being essentialso that the rotor can exert the necessary torque on the mainshaft. Otherlobe combinations can theoretically be used, but the one outlinedappears to have been universally adopted.

Because of this eccentric mounting the rotor moves within the chamber inwhat is usually described as an orbital motion, which may be regarded asa combination of circular and pulsating motions of the rotor.

The rotation of the rotor on its bearing must be phased accurately withits motion in the chamber in order to provide a plurality of workingchambers that vary in volume in the required manner upon relativerotation of the rotor and chamber. The current practice with theWankel-type engine as described in the Wankel specification, thedisclosure of which is incorporated herein by reference, is to providethe necessary phasing by means of an internal-toothed ring gear rigidlyattached to the rotor meshing with a pinion reaction gear rigidlyattached to the casing. With said universally adopted lobe configurationif the ring gear has 72 teeth then the reaction gear must have 48 teethto produce a 3:2 ratio between them.

One of the problems encountered with the Wankel engine has been coolingof the rotor, and the solution often adopted has been to provide heattransferr to an external radiator by means of controlled pressurecirculation of oil to and from the rotor. An arrangement for circulatingcooling oil within the rotor interior is described and claimed in US.Pat. Ser. No: 3,102,683, issued Sept. 3, 1963 to N.S.U. Moterenwerke AG.and Wankel G.m.b.H. 1n the disclosed arrangement oil is fed to a chamberwithin the rotor interior where it performs its intended coolingfunction. The oil is distributed by centrifugal forces around theinterior surface of this chamber in the form of a film thereof, and theoil is removed from the chamber while the thickness of this film ismaintained at a constant value by the provision of a stationary discwhich extends into the chamber. The shape of the disc peripherycorresponds to the figure swept by the oil-receiving rotor internalchamber with provisions for maintaining the said oil film thickness, thedisc having radially extending channels with openings that intercept theoil, so that it is forced through the openings into the channels andconveyed to another part of the engine (e.g., the casing and/or acooler).

DEFINITION OF THE INVENTION It is an object of the invention to providea new rotaty mechanism of the type comprising a three-lobed rotor oftriangular crosssection operative within a two-lobed chamber ofepitrochoidal cross-section.

It is a more specific object to provide a new rotaty mechanism of thetype specified in the preceding paragraph, and comprising a new meansfor maintaining the rotor in correctly phased orbital motion within itschamber. It is a further object of the invention to provide a new rotaryengine having an internal chamber of K value about 5.

In accordance with the present invention there is provided a rotarymechanism comprising a body, a shaft mounted by the body for rotationabout a corresponding axis, the body providing an internal chamberhaving an internal peripheral surface of two-lobed epitrochoidalcross-section perpendicular to and symmetrical about the said shaftaxis, a threelobed rotor of triangular cross-section mounted within thechamber for rotation about an axis displaced from and parallel to thesaid shaft axis, eccentric means connecting the shaft and the rotor fortransmission of rotation between them, the rotor being symmetrical aboutits own axis and having a plurality of three circumferentiallyshapedapex portions in sealing engagement with the said chamber internalperipheral surface to form a plurality of three working chambers betweenthe rotor external peripheral surface and the chamber surface that varyin volume upon relative rotation of the rotor and the chamber, andguidance means for guiding the rotor in the required motion relaive tothe casing comprising a first essentially triangular guide surfacemovable with the rotor, symmetric about the rotor axis, and parallel tothe rotor axis, and a second guide surface movable with the body,symmetric about the shaft axis, and parallel to the shaft axis, theguide surfaces being in relatively-sliding engagement with one another,the said second surface being the oval shape generated by the said firstsurface in their required relative motion and having its major and minoraxes parallel respectively to the minor and major axes of the internalbody surface.

Preferably in a rotary engine the said internal chamber has a K value of5.

DESCRIPTION OF THE DRAWINGS Particular preferred embodiments of theinvention will now be described, by way of example, with reference tothe accompanying diagrammatic drawings, wherein:

FIG. 1 is an exploded view of one rotary mechanism operable as a motoror pump, the mechanism being shown exploded along the axis of rotationof the mainshaft thereof.

FIGS. 2 to 5 are schematic cross-section views on the line 2-2 of FIG. 1to show the different positions that can be taken by the rotor relativeto the chamber in which it is located, and the corresponding positionsrelative to the members constituting the guidance means,

FIG. 6 is a cross-section view on the line 6-6 of FIG.

2 and showing the mechanism in assembled condition,

FIG. 7 is a cross-sectional view through one of the rotor apices,perpendicular to the axis of rotation thereof, in order to show detailof the construction of the apex seals employed with the rotor,

FIGS. 8 and 9 are schematics of internal epitrochoidal paths in order toshow certain limits in the geometry of the path that can be used, and

FIGS. 10 to 16 are graphs comparing the characteristics of known rotaryengines with those that can be produced employing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As indicated above the rotarymechanism illustrated herein very schematically as a particularpreferred embodiment may be employed as an engine or a compressor and,depending upon the particular application, will require certainadditional equipment (such as a carburettor, oil-cooler, etc.) whosedescription is omitted since it is not essential for full ilustrationand understanding of the present invention. The nature andcharacteristics of such additional equipment required will be apparentto those skilled in the art.

The mechanism consists of an outer casing indicated generally by thereference 10 and constituted by a pcripheral part 12 and two end plates14 and 16 fastened thereto by any suitable means, for example, bythrough-bolts 17. The casing provides an internal chamber 18 whoseinternal periphery 20 is symmetrical about a central longitudinal axis22, the said periphery being of two-lobed epitrochoidal cross-sectionperpendicular to the axis 22. Bearings 24 in the end plates support amainshaft 26 for rotation about an axis coincident with the axis 22. Theshaft is provided with an eccentric portion 28 which is integraltherewith or rigidly attached thereto, the eccentric portion being ofcircular cross-section perpendicular to a longitudinal axis 30, which isparallel to the axis 22 and spaced a distance r (FIG. 6) therefrom. Thisdistance r is the effective eccentricity of the mechanism.

A three-lobed rotor indicated generally by the reference 32 is mountedby bearing part 34 for free rotation on the shaft eccentric portion 28,so that it can move in the so-called orbital or planetary motion withinthe chamber 18 as the shaft rotates. In this embodiment the rotor 32 hasan external periphery constituted by three side walls 36 meeting atthree corresponding apices 38, each apex being provided with acorresponding apex seal indicated generally by the reference 40. Theseseals are omitted from FIGS. 2 to 6 for simplicity of illustration. Theexternal periphery of the rotor is of general equilateral trianglecross-section perpendicular to its axis and symmetrical about that axis,the sidewalls 36 being however slightly arcuate radially outwards andnot straight. Working fluid can be introduced into the part of thechamber 18 not occupied by the rotor via an inlet 42 in the end plate 14and removed via an outlet 43 in the member 12. The mechanism is alsoillustrated as comprising an ignition device 44 mounted in acorresponding opening 45, although other forms of device, or otherignition means (e.g., when the mechanism is a diesel engine) can beemployed. Such a device is of course not required when the mechanism isa pump.

The structure so far described is also the basic structure of the Wankelrotary engine. As the rotor moves in its orbital motion a plurality ofworking chambers are formed between the walls 20 and 36 that varycyclically in volume. The operation of the device either as an engine oras a compressor is now so well known as not to require furtherdescription. In the Wankel engine however the rotor and main shaft areprovided respectively with an'internally-toothed ring gear and anexternally-toothed pinion gearthat mesh with one another, the piniongear being fixed to the end plate coaxially with and surrounding themainshaft, and thereby serve to phase or register the position of therotor with respect to the inner peripheral surface 20 as the rotor movesin its orbital motion. This gearing has the function of rotating thecentre of mass of the rotor in a circular path of radius r and at twicethe mean angular velocity of the rotor apices, reacting against theinertial forces of the rotor and thereby taking the positioning loadthat would otherwise be applied to the apex portions of the rotor.

In a mechanism in accordance with the invention the necessary guideconnection between the rotor and the casing 10, in order to ensure thatthe rotor is guided in the required motion relative to the casing, isproduced by two freely relatively-sliding bearing guide surfaces 46 and48 provided respectively on the casing and rotor. In this particularembodiment the rotor guide surface 48 is constituted by the innerperiphery of a recess 50 in one side wall of the rotor, while the casingguide surface 46 is provided by the external periphery of a core guidemember 52 fixed to the end plate 14 and protruding into the recess 50.The surfaces 46 and 48 are symmetrical about their respective axes andone of them must be the minimum boundary figure that is circumscribed bythe other in the required orbital motion of the rotor within the casing.It is also an essential condition for this embodiment that one of thesurfaces shall be shaped to conform to a specific mathematical curvewhich will result in a two-lobed oval-like form for that surface, sothat the two co-operating guide surfaces will be operative to providethe necessary restraint and guidance between the relatively movableparts.

The rotor internal guide surface 48 has the form of an equilateraltriangle contained within the shape of the rotor external periphery. Itis then found that the corresponding casing guide surface 46 of the coreguide member is an oval with major and minor axes parallel respectivelyto the minor and major axes of the casing epitrochoidal surface 20. Sideseals (not shown) will be provided which co-operate with the apex sealsto seal off the variable-volume working chambers from one another andfrom the remainder of the chamber 18. The construction of such sideseals will be known to those skilled in the art.

A recess 51 similar to the recess 50 is provided in the other rotor sidewall for balance, but may instead or in addition provide a guideconnection surface.

One of the essential parameters to be considered for rotary mechanism ofthe type to which this invention applies is known as the K factor, whichis the ratio 2r,/r where 2r, is the maximum rotor .radius and r is theeccentricity thereof. .I will show that rotary engines previouslyproposed have operated with K values for the chamber of greater than 6,usually about 7, while I am able with my invention to provide a K valuepreferably of 5, which will be shown to have very substantial designadvantages.

FIGS. 2 to 5 show some of the different relative positions that areoccupied by the rotor in the chamber 18 (one of the lobes beingindicated by a dot so that its movements are more easily followed) andthe corresponding relative positions occupied by the core guide surface46 in engagement with rotor guide surface 48. It is difficult to makedrawings at this small scale which will allow illustration of the exactrelation of the guide surfaces 46 and 48 to be visually observed, sincethe clearances obtained frequently are very small. To facilitateexplanation of the actual sequence of events, I use the term indexing toindicate that three places on surface 48 are in contact with surface 46,while I use the term guiding to imply that only two places of contactexist. Small circles shown on the rotor face are indicators of contactplace locations when K=5. Thus in the relative positions illustrated byFIGS. 2 and 5 the rotor is indexing, while in all other positions therotor is controlled by guiding in its dynamic motion. On the other handif K=6 or any larger value the rotor is indexing in all positions. Inboth control modes rotor stability is preserved. Since the shape of thesurface 46 is that generated by the movement of the surface 48 in therequired motion, then the rotor is constrained to follow only thatmotion, resulting in an ordered sequence of relative sliding motion inwhich Zero sliding or even some retrogression is possible during theoperation of the engine or compressor.

The apex seals 40 are required to provide the necessary sealing underthe extremely arduous conditions encountered in a rotary engine, and thedevelopment of such seals has been crucial in the production of acommercially acceptable engine. FIG. 7 shows in crosssection aparticularly advantageous seal structure wherein two axially-extendingseal members 54, of what can be described as of boomerang transversecross-section, have their two convex faces abutting one another, withcorresponding outer end parts extending radially from the rotor and withcorresponding inner end parts thereof engaged in a respectiveaxiallyextending longitudinal slot 56. The innermost edge of each member54 is provided with a suitable gas seal 57 and gas-conveying passages 58lead from an opening 59 in a respective rotor face 36 to the bottom ofthe opposite slot.

If it is assumed for example that the rotor is rotating clockwise asseen in FIG. 2, then the surface 36a is the leading surface with respectto its associated seal. The pressurised gas in the respective workingchamber will flow through the respective passage 58a to the connectedslot 560 and force the seal member 54a radially outwards in its slot inthe direction to reduce, or at least maintain, the leaning angle (i.e.,the angle of inclination of the seal to the stator wall) at apredetermined value. Assuming that the gases at the face 36a are theexpanded igniting gases then as the seal passes over the cusp of thecasing epitrochoidal inner wall, the gasses will now be exhausted fromthe passage 58a by the engine exhaust action while pressurised gas willbe applied through the passage 58b, reversing the direction of the gasaction on the seal.

It can be shown that a single vertical seal would have a maximum leaningangle of 37, whereas an angle of less than 30 is desired; a seal inaccordance with the invention is operable with angles no greater than22.

The seal is lubricated automatically by means of a ball valve 60operative in a radial bore 62 and connecting a space 64 between theabutting seal member faces with the interior space 66 of the rotor.During portions of the rotor motion centrifugal force will be effectiveto force oil through the passage 62 past the open ball valve to thespace 64 and thence between the seal members 54; upon reversal of theforce during other parts of the motion the ball valve closes to preventdrainage of oil from the space 64.

In the interest of establishing a valid basis for comparison of myguidance means with existing means it is necessary to consider themathematical foundation which supports each of them.

It is possible to avoid misunderstanding which may occur when differentK factors are used for designing the guidance means and fixing the sizeof the rotor. The analysis is no less general in its conclusion byapplying the simplifying condition that the same K factor is assumed toapply.

The geometry of the epitrochoid is elaborated in Norbyes book, and hisstatement of the necessary ratio of the annular ring gear to thereaction pinion gear of 3:2, has also been mentioned earlier. Bygeometeric construction the annular gear has a radius r and the reactiongear radius r r and their necessary relation results in the equality:

In a three-lobed rotor based on an equilateral triangle the length ofthe longest radius must always be twice that of the shortest radius rand since K 2r /r the above result is that k 6.

A requirement I believe that must be met in practice is illustrated byFIGS. 8 and 9, which show the internal epitrochoidal paths generated bythe short radius of the rotor triangle at is point of intersection withthe midpoint of one side of the rotor triangle for two different ratiosof a and b, where a is the major axis and b is the minor axis. Thereversal of motion indicated by FIG. 8 cannot take place, since it wouldinvolve retrogression of the pinion in its engagement with the ringgear, and would result in jamming or even stripping thereof. The motionillustrated by FIG. 9 is therefore a limiting condition for a Wankeltype engine, establishing the relation tha must be satisfied in thedesign of this ring gear and pinion, since (1) (n e)/( 1 H) 2 in whichagain the value of r r /3 as stated above.

The epitrochoidial path of the generating point on the periphery of theannular ring is illustrated by FIG. 9, in which a simple cusp occurs ateach end of the short axis and represents an angular change in motionbut not a retrogade motion. Thus the mathematical solution is confimedby the physical impossibility of such reversal occurring at place ofengagement of the gear teeth. Having obtained the actual K factor forconventional guidance means it is possible to find solutions for allproposed design applications. For example the present generation ofrotary engines is operative with a k factor that usually is about 7 inrespect to the epitrochoidal body, while the guidance system isdiminished in size to make its effective K factor equal to 6.

This problem does not arise with the guidance system of this invention,since the engagement between the guidance members is by sliding engagingsurfaces, which will permit some retrograde motion, as illustrated bythe curve of FIG. 8. It is thereforee possible to construct a mechanismin accordance with the invention with a K value lower than ,6, which isin itself a substantial design advantage.

An analysis of the rotary engines at-presentfcorhmercially availableshows that all of 'them-thave anepitrochoidal chamber of K-factor muchgreater than 6, and the figures which I have been able to obtain appearto show a range of K-factor' from about 6.73 to about 7.14. It is atpresent believed that a probable reason for this is that, as isillustrated by FIG. 9, a K factor of 6 represents a unique value for theuniversally used three-lobed rotor and two-lobed stator, which involvesstationary or almost stationary relative motion between the rotor andstator twice for each of three points on the rotor midway between theapices, making a total of six occasions in each rotation of the rotor.This theoretical observation correlates with the practical observationthat as the K factor decreases toward the value 6 there is a tendencyfor the rotor to flutter" or chatter, indicating severe instability inits motion. It can be shown that for a k value of 6 the period ofstationary or near stationary motion can extend over an angle as greatas ten degrees on each occasion. A practical result of this particularflutter or chatter instability, besides the objectionable noise,vibration and possible damage to the bearings, is a breakdown of thelubricating oil film on the stator surface and consequent scoring andsevere damage thereto.

An examination of FIG. 8 will show that, although there are sixreversals of motion in each rotor revolution, these do not involveintermediate instable unique locations, but instead take place smoothlyand progressively. As explained above the gear type guidance means usedhitherto cannot function at a K value other than 6, and therefore it hasnever been possible with suchengines to pass beyond this highly unstablevalue to the more stable and preferred value of 5.

The mechanism illustrated by FIGS. 2 to has a K value of 5 and, asdescribed, the small circles show the contact locations for the guidancesurfaces for this value. As explained, although the rotor only is ben'gindexed at two locations, being the two locations at which reversal ofmotion takes place, and is being guided at all other locations, rotorstability is assured during the entire cycle of each rotation.

In general mechanism in accordance with this invention may employ anyvalue of K factor contained within the range K at infinity to K equal 5avoiding the apparently uniquely unstable value 6. As a practical matteruseful power is concentrated in a limited range where k is not greaterthan 10. Also in practical terms the preservation of a stable pattern ofmotion must be sustained. By referring to FIGS. 2 and 5 it can be seenthat there are a maximum of three points of contact betweeen therotating and the fixed surfaces. The positions of the rotor show thatthe extreme end points of the fixed guide surface as well as one pointon its short axis are in simultaneous contact with surfaces on therotor. It can be inferred that this condition confers an exact indexingfunction on the guidance system which is necessary to preservestability. A limit value for k for mechanisms of this invention can beobtained by solving the general equation for the core guide surface withthe rotor in the position of FIGS. 2 or 5. The known relations are thatwhen qb 17/ 3 the valueof x 0, where x is the abscissa. The equation isx [(K -4)+2 cos 2 4)] (r cos 4)) (l/K) and O K4-l therefore K 5 Likewiseit can be deduced that stability is also preserved for all otherpositions, in view of the nature of the general equation, within thelimits specified, namely that (l) the curve is a continuous functionbetween the ends of its major axis; (2) it has no singular points orinflections between these limits; and (3) it is symmetrical about itsmajor axis. The rotor can be shown to have balanced relationship ofdynamic and mechanical stability, since the path of the rotors centre ofgravity is in uniform circular motion under continuous surveillence oftwo opposed surfaces providing guidance with mechanical exactitude.

The effect of this possible reduction in K factor is illustrated byFIGS. 10 and 16, which show graphs of computations involving four cycleinternal combustion engines of K factors from 5 to 7. In each case thefollowing limits are used to permit direct comparison:

a. Compression ratio is 10 and is constant b. Rotor is measured as anequilateral triangle with c. The rotor short radius is r d. The rotorlong radius is 2r e. The radius of eccentricity r in terms of K is 2r,/K

f. Rotor width is subject to designers choice, but for these examplesits specific value is fixed as 3r l/K g. Displacement volume V h. Volumeof chamber 18 absolute volume V i. The equation for V 241rr /K (K +3) j.The equation for V 80 fin /K FIG. 10 shows the increase in rotor surfacearea and working stroke, both of which are functions of K, with decreaseof K, while FIG. 11 shows the increase in displacement volume V of therotor (equivalent to piston displacement in a pistion engine) comparedto the increase in total available volume in the epitrochoidal chamber18. FIG. 12 combines the results of FIGS. 10 and 11 and shows that threerotors of K 5 should be capable of the same output as four rotors of K7.

FIGS. l3to 16 show the expected performace of engines of the same size,but having differing K factors. FIG. 13 plots the value of V which is inthis example a constant, the load factors causing friction (which arefound to correspond to V and the relative radii of the rotating parts.FIG. 14 is a plot of the gross power factor and the value of V is ameasure of this, since the compression ratio is constant. FIG. 15 showsthe friction power loss computed using the factors of FIG. 11, and thenet power factor N which is the result of subtracting friction powerloss from gross power. It will be seen than N at K 7 has the relativevalue 1.0, while at K 5 it has become 1.6, so that on this basis tworotors of K 5 should have the net power output of three rotors of K 7.The efficiency factor of an engine is an indication of the power to beobtained from a unit quantity of fuel, and is expressed by the relationN/V A plot of this factor is shown in FIG. 16. The increasing factorshows that increased power is obtained per unit size of engine as K isdecreased from 7 to 5.

At this time I am not aware of any discussion of the problem of anadequate performance rating formula which would serve as a standard ofcomparison between different rotary mechanisms. This problem differsfrom the subject of the comparison of rotary mechanisms with piston typemechanisms, which has been treated in detail. The increased scope forimprovement in rotary mechanism design has disclosed the need for astandard rating formula, which will be adequate as a guide to and ameasure of the progress in rotary mechanism development.

A formula is required to measure the efficiency with which the availablevolume is utilized for useful work. It is a noteworthy feature of amechanism in accordance with the invention that substantially all itsinternal volume appears to be available for the work cycle, as thoughits moving parts had vanished. This entire internal volume is calledAbsolute Volume for that reason and is denoted as VT. The displacementvolume must take into account the compression ratio, (denoted by theletter n) and is termed V,, The number of power impulses is three perrotor revolution. Then Absolute Volumeteric Efficiency Ratio is givenby:

Using the convention set out above and with n=l0, the tabulation of theratio as a percentage is:

K=7 K=6 K=5 s, 74.0% 84.8% 98.5%

If a compression ratio of 8.8 is employed when the K factor is 5, then 6100 percent, showing that such a ratio theoretically is obtainable in apractical mechanism.

The invention is applicable to mechanisms which are engines or pumps orcompressors, and the engines may be of any known cycle, such as 2 or 4cycle, with or without compound cycles or supercharging. More than onerotor may be mounted on a single shaft and units may be employed inmultiples. The engine may be of internal or external combustion type.

I claim:

1. A rotary mechanism comprising a body, a shaft mounted by the body forrotation about a corresponding axis, the body providing an internalchamber having an internal peripheral surface of two-lobed epitrochoidalcrosssection perpendicular to and symmetrical about the said shaft axis,a three-lobed rotor of triangular cross-section mounted within thechamber for rotation about an axis displaced from and parallel to thesaid shaft axis, eccentric means connecting the shaft and the rotor fortransmission of rotation between them, the rotor being symmetrical aboutits own axis and having three circumferentially-spaced apex portions insealing engagement with the said chamber internal peripheral surface toform three working chambers between the rotor external peripheralsurface and the chamber surface that vary in volume upon relativerotation of the rotor and the chamber, and guidance means for guidingthe rotor in the required motion relative to the casing comprising afirst essentially triangular guide surface movable with the rotor,symmetric about the rotor axis, and parallel to the rotor axis and asecond guide surface movable with the body, symmetric about the shaftaxis, and parallel to the shaft axis, the guide surfaces being inrelatively-sliding en gagement with one another, the said second surfacebeing of the oval shape generated by the said first surface in theirrequired relative motion and having its major and minor axes parallelrespectively to the minor and major axes of the internal body surface.

2. A rotary mechanism as claimed in claim 1, wherein the first surfaceis provided by a recess in the rotor and the second surface is providedby a member extending into the said recess.

3. A rotary mechanism as claimed in claim 2, wherein the said guidancemeans has a K value of about 5.

4. A rotary mechanism as claimed in claim 3, and comprising a rotaryengine wherein the said internal chamber of the body and the rotor havea K value of 5.

5. A rotary mechanism as claimed in claim 1, wherein the said guidancemeans has a K value of about 5.

6. A rotary mechanism as claimed in claim 5, and comprising a rotaryengine wherein the said internal chamber of the body and the rotor havea K value of 5.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,600Dated May 20, 1975 Inventor s Herbert Lewis Gray It is certified thaterror appears in the ab0veidentified patent and that said Letters Patentare hereby corrected as shown below:

In the drawings, Sheet 1, Fig. 1, reference lines 22 should be appliedto indicate vertical section through peripheral part 12.

Column 6, line 26, the formula "3r 2 (r r should read l l e --2r 3 (r rColumn 8, line 29 the portion of the formula reading "247Tr K (K 3)"should read --24'rfr (K 3)/K Change the title from "GUIDANCE MEANS FOR AROTARY ENGINE OR PUMP" t0 -'ROTARY ENGINES AND PUMPS WITH GEARLESS ROTORGUIDANCE MEANS- Signed and Scaled this Thirty-first Day of May 1977[SEAL] RUTH c. MASON c. MARSHALL DANN AN J IX Office Commissioneroflarents and Trademarks

1. A rotary mechanism comprising a body, a shaft mounted by the body forrotation about a corresponding axis, the body providing an internalchamber having an internal peripheral surface of twolobed epitrochoidalcross-section perpendicUlar to and symmetrical about the said shaftaxis, a three-lobed rotor of triangular cross-section mounted within thechamber for rotation about an axis displaced from and parallel to thesaid shaft axis, eccentric means connecting the shaft and the rotor fortransmission of rotation between them, the rotor being symmetrical aboutits own axis and having three circumferentially-spaced apex portions insealing engagement with the said chamber internal peripheral surface toform three working chambers between the rotor external peripheralsurface and the chamber surface that vary in volume upon relativerotation of the rotor and the chamber, and guidance means for guidingthe rotor in the required motion relative to the casing comprising afirst essentially triangular guide surface movable with the rotor,symmetric about the rotor axis, and parallel to the rotor axis and asecond guide surface movable with the body, symmetric about the shaftaxis, and parallel to the shaft axis, the guide surfaces being inrelatively-sliding engagement with one another, the said second surfacebeing of the oval shape generated by the said first surface in theirrequired relative motion and having its major and minor axes parallelrespectively to the minor and major axes of the internal body surface.2. A rotary mechanism as claimed in claim 1, wherein the first surfaceis provided by a recess in the rotor and the second surface is providedby a member extending into the said recess.
 3. A rotary mechanism asclaimed in claim 2, wherein the said guidance means has a K value ofabout
 5. 4. A rotary mechanism as claimed in claim 3, and comprising arotary engine wherein the said internal chamber of the body and therotor have a K value of
 5. 5. A rotary mechanism as claimed in claim 1,wherein the said guidance means has a K value of about
 5. 6. A rotarymechanism as claimed in claim 5, and comprising a rotary engine whereinthe said internal chamber of the body and the rotor have a K value of 5.